Many devices, such as missiles and guns, vibrate upon being actuated (fired). This post-actuation vibration phenomenon is associated with the inertia of the bolt action of the weapon and can affect the performance of the gunfire rate. The bolt occurs due to the force generated by firing the round which pushes the bolt rearward to engage the next round and load it into the chamber. The operation of a given weapon occurs at a specified firing rate. If the vibration of the mount on which the weapon is mounted is out of phase with the operation of the bolt, then the inertia associated with the bolt motion can be reduced which, in turn, can reduce the rate of fire and performance efficiency of the weapon. A stable mount with a desired natural frequency would enable optimal performance of the weapon.
In cases of weapons which are too heavy to be mounted directly onto the roof of some combat vehicles, a mount is needed to support the weapons from inside the vehicles and still allow the weapons to be exposed at the roof level.